We observed several protostellar collapse candidates
in the HCO^+ 1-0 and HCN 1-0 lines
using the BIMA interferometer.
These sources were selected from their infall signature
(the blue side is stronger than the red side)
in a single-dish survey of Class 0 sources
(Gregersen et al. 1997).
In our HCO^+ 1-0 and HCN 1-0 spectra,
all the sources show the blue side
stronger than the red side,
which is consistent with the selection criteria.
Only four of them (L1527, HH25MMS, IRAS16293, and B335),
however, show spectra with double peaks,
consistent with infall models.
The others (NGC1333 IRAS4A, NGC1333 IRAS4B, Serpens SMM4,
Serpens SMM2, IRAS20050, and L1157)
do not show detectable red peaks.
Detailed radiative transfer calculations are needed
to test if these blue-peak only spectra
are consistent with infall models.